Restaurants, health centers and convenience stores dealt with a flurry of activity after yesterday’s rupture of a water pipe led the state to issue a “boil-water order,” something Gov. Deval Patrick said would last several days.

Today workers began the process of replacing a missing joint on the pipe in Weston that caused the leak. Though the cause of the break is still unknown, the state hopes to have the project finished tonight and the boil water order ended several days after, said Joshua Das, the public-health manager for the Massachusetts Water Resources Authority.

“Nothing is set in stone yet,” Das said.

If the structure of the pipe is compromised, Das said, it would have to be replaced, which could take “quite some time.” Das would not give an estimate for this time, saying that it depended on the extent of the pipe’s damage.

For many restaurants and other food establishments, the order dramatically interfered with normal business operations.

“We’re a bakery, we need water to make all our breads,” said Matt Litson, a baker at Au Soleil Bakery. “We go upwards of 200 gallons a day.”

Litson said it has been a major inconvenience to boil the water before it is used, both in the bakery and in its sister restaurants, Sel de la Terre and L’Espalier.

“You need water pretty much for everything, washing vegetables, cooking,” Litson said.

Convenience and grocery stores saw a run on bottled water after the announcement was made, something many said continued today.

“We’re going to run out by tonight,” said an employee at the CVS at 900 Commonwealth Avenue who asked remained anonymous because workers are not supposed to speak to the media.

“We’re supposed to be getting more in today, but they haven’t really given us an idea of when we’re going to be getting it,” the employee added.

Most people have been trying to buy larger bottles, but we’ve run out of those, so they have been buying more smaller bottles now,” said an employee at City Convenience in Kenmore Square, who asked to remain anonymous because employees have been instructed not to speak with the press.

City Convenience “should be getting more in tomorrow,” the employee said.

Because unclean tap water is especially dangerous to those with compromised immune systems, health centers across the Boston area took extra precautions to avoid exposure.

At Massachusetts General Hospital, a letter sent to the community stated “immunocompromised patients should not shower until the situation has been resolved” among other suggestions to visitors and patients.

On its website, the Massachusetts Department of Environmental Protection advises people to boil water in heat-resistant containers for one minute to “kill all disease-causing organisms.”

People can also use microwaves if there is a “glass rod or wooden or plastic stir stick in the container to prevent the formation of superheated water” but that boiling water in a microwave can be dangerous, according to the website.

At Boston University, RAs handed out bottled water to students entering the dining halls. Inside, soda, juice and coffee machines were shut off. Some campus dining establishments like Starbucks closed for the day.

But BU spokesman Colin Riley said the university would weather the emergency.

“The fact is we think we’ll have sufficient water coming in every day,” Riley said.

Students said the situation was more of an inconvenience than a major concern.

“I think BU responded pretty well to the crisis,” said Sargent College of Health and Rehabilitation Sciences senior Collette Friedenson said. “It’s just poor timing because the weather is so hot and people are moving out soon so it’s chaotic.”

Friedenson said she purchased four gallons of water and boiled water to set aside for brushing her teeth with.

College of Arts and Sciences junior Genna Helfriche said she is utilizing what BU is offering.

“I went to the dining hall and stocked up on water,” she said. “It sucks that it happened when it’s hot out…but the Department of Public Health has things under control and BU reacted fast. I think the biggest problem is no coffee in the dining halls during finals week.”

Staff writers Saba Hamedy and Suzanne Schiavone contributed reporting to this article.